Hey SteevoLS, welcome back. If you haven't done any themeing in a couple of years I think you might have missed the xModules, which is the greatest thing that has happened to LS since... well, ever :)

First of all it's xLabel, which is a very powerful module based on Maduin's Label. You can do lots and lots of cool stuff with it; buttons, bars, moveable boxes (no one's using lsbox anymore :)), animations -- you name it. It also has really advanced solid color support, so nowadays you can make great-looking themes without using one single image. There's also xPopup and xTaskbar, which have similar capabilities. I suggest you head over to ls-universe.info and ask around in the forum.

There's also a module called LSLua that has become highly popular. It lets you use the Lua language to script stuff in LS. Can't really tell you much more about that since I'm not using it, but if you need more advanced scripting power than what mzscript can provide, you should check out LSLua.

As for builds, the latest offical one is 0.24.7 final, but there's also an experimental build with some new features around that is very stable, AFAIK there's a lot of people using it.

Finally, there's a new installer called LOSI being developed. Not sure when it'll be released, but it'll incorporate the new OTS3 standard.

So as you can see, a lot of stuff has happened and LS is more powerful than ever. If you want to check out what can be done with the "new" LS, try d/l-ing some themes by xcal, fractal.design or Cerbie. Ashtefere is also doing a lot of advanced visual stuff, and jqubit has released a couple of themes that take usability and interaction to new levels.

And oh, LS also has a wiki nowadays. It's probably a good place to start for getting up to speed.